Archive for the ‘Opportunistic Infections’ Category

The relative importance of NK cells in lung defense against cryptococcal disease may also be dependent on the route of inoculation of the organism. Previous investigators demonstrated a role for NK cells in cryptococcal resistance using an intravenous inoculation model. We studied the role of NK cells in the resistance to cryptococcal infections in mice […]

We have investigated two natural defense mechanisms, NK cells and a complement-dependent mechanism, where the route of inoculation of the organism made a critical difference in outcome. Previous studies documented that mice deficient in the C5 component of serum complement were particularly susceptible to C neoformans if the organism was inoculated intravenously. The predominant defect […]

To study the effect of CMI in the lung, it was essential to develop a lung infection model whereby the organism initially grew in the lung and at about the time immunity should develop, enhanced resistance would be manifested. In initial studies, intratracheal inoculation of a strain of C neoformans known to be extremely virulent […]

Cryptococcus neojbrmans Intact CMI is essential for host defense against C neoformans although it is likely NK cells, PMN, and macrophages provide some protection in a T-cell-deficient host. Our laboratory has been using C neoformans in a murine model to explore how CMI regulates pulmonary defense mechanisms. Several experiments pointed to important variables in experimental […]

Pneumocystis carinii Pneumocystis carinii is difficult to study because long-term culture has been largely unsuccessful. Infectious models depend on prolonged immunosuppression, usually with corticosteroids, of experimental animals likely harboring endogenous organisms. Studies in rats free of endogenous infection have demonstrated that the initial route of a Pneumocystis infection is aerogenous, and morphologic studies using the […]

Protection was measured by numbers of organisms in the spleen and also required the presence of host CD4, but not CD8, T cells. Another study, also using an intravenous inoculation model and measuring splenic rather than pulmonary tubercle bacillus load, demonstrated that depleting mice of CD4 cells with an appropriate monoclonal antibody decreased resistance to […]

Mycobacterium tuberculosis Tuberculosis is not usually considered an opportunistic infection, although the disease is far more devastating in T-cell-suppressed patients. Like Listeria, the organism resides in phagocytes in the host. Healthy individuals exposed to M tuberculosis generally have mild or completely asymptomatic primary infections. Although the mechanisms remain ill defined, loss of resistance may result […]

Lessons Using a Listeria monocytogenes Model In the early 1960s, the murine L monocytogenes model was used to gain an understanding of CMI in the human host. George Mackaness and coworkers associated acquired resistance to L monocytogenes with the development of “activated” macrophages. Several days after an intravenous inoculation of Listeria, spleen cell suspensions could […]